This striking decor is documented in Collectible Bohemian Glass, 1880-1940, by Robert and Deborah Truitt, in which they show two examples... one unadorned vase, and the other, a bowl in a metal mounting. This example has exquisite silver overlay typical of the heyday of the jugendstil period - 1895-1900. The decor is coined as "matte ceramic", presumably because of its similarity to glazed ceramics. Harrach made extensive use of uranium in opaque glass pieces during this time - late 1800's to early 1900's - for reasons unknown (certainly not exclusively as a colorant, as it was used as a liner in cased pieces and also in pieces that, through careful use of temperature and skill, became an opaque white to pale custard yellow). It is my guess that it was done to give the glass a certain "heft" and texture similar to that of fine porcelain. The base glass in this piece is aqua/turquoise blue, with a high contrast burgundy stain brushed onto the surface. The silver overlay adds interest to this piece without overpowering the glass, as can sometimes be the case with art nouveau overlay.